DE102009022598A1 - Human eye's absolute measuring value determining method, involves reconstructing medium of eye by local scaling factors such that two-dimensional or three-dimensional representation of medium of eye comprises absolute measuring values - Google Patents

Abstract

The method involves comparing geometric characteristics of structures of a medium of an eye with geometric characteristics, which are reconstructed from measuring data of local deep-scan and/or A-scan. Local scaling factors are determined from the determined comparison of the geometric characteristics. The medium of the eye is reconstructed by the local scaling factors in such a manner that two-dimensional representation or three-dimensional representation of the medium of the eye comprises absolute measuring values in all directions.

Description

The The present invention relates to a method for determining absolute, highly accurate measurements of the known features of the structures of an eye, especially its retina and anterior chamber.

to Determining the known features of the structures of an eye there in the prior art, a number of known methods and measuring devices, for this purpose, especially ultrasound and optical Measuring instruments based on short-coherent methods have enforced.

at There are two different embodiments of the ultrasound devices either according to the so-called "A-Scan" principle or work on the "B-scan" principle. While the A-scan only one measurement in the axial direction, d. H. in depth, An additional measurement in transversal takes place during B-scan Direction. The ultrasound procedure basically requires direct contact with the eye.

In the DE 42 35 079 C2 For this purpose, a device for examining the eye, in particular the human eye is described, which is essentially a frusto-conical holder, adapted to the eye shape, which has inside a probe for the evaluation of acoustic (ultrasonic) signals. The probe is inclined relative to the central axis of the holder and suitable both for transmitting and for receiving pulse-shaped signals.

The specific disadvantages of ultrasound devices lie to one in a lesser accuracy and on the other in need direct contact with the eye, which is always a risk to involves the transmission of infections and the other it is necessary the eye for the measured value determination to anesthetize. As with ultrasound machines a Alignment to the visual axis of the eye is not automatic, If necessary, special resources should be provided for this purpose.

Analogous to the ultrasound machines, where by the acoustic Signals images of the structure transitions reconstructed be based on the optical gauges short coherent method optical images of the structure transitions represented as two-dimensional depth sectional images. As short-coherent Measuring method has in this case the so-called OCT method (OCT = optical coherence tomography), in which coherent Light with the help of an interferometer for distance measurement reflexive and scattering materials is used. Optical Coherence Tomography at human eye delivers depth when scanning, due to changes measurable signal responses in the refractive index at all optical interfaces.

This example in US 5,321,501 The basic principle of the OCT method described is based on white-light interferometry and compares the transit time of a signal with the aid of an interferometer (usually Michelson interferometer). The arm with known optical path length (= reference arm) is used as a reference to the measuring arm. The interference of the signals from both arms gives a pattern from which one can read the relative optical path length within an A-scan (single depth signal). In the one-dimensional scanning methods, the beam is then transversely guided in one or two directions analogously to ultrasound technology, with which a planar B-scan or a three-dimensional tomogram (C-scan) can be recorded.

at The OCT methods used in ophthalmology have two enforced different types. To determine the measured values, the first type of reference arm changed in length and continuously measured the intensity of the interference, without taking the spectrum into account. This Procedure is referred to as "time domain" method. In the other, called "Frequency Domain" Method, on the other hand, the spectrum is determined to determine the measured values and the interference of the individual spectral Components detected. Therefore one speaks on the one hand of the signal in the time domain and, on the other hand, the signal in the frequency domain.

Of the Advantage of the "Frequency Domain" method lies in the simple and fast simultaneous measurement, being complete Information about the depth can be determined without requiring moving parts. This increases the stability and the speed.

The "Frequency Domain "method is dependent the light source used in simultaneous and sequential procedures divide. The simultaneous, requiring a broadband light source Procedure is also called "(Parallel) Spectral Domain" procedure wherein the so-called "Fourier (Transform)" method represents another subgroup. In contrast, at the simultaneous Process a tunable light source with variable Wavelength, where the sequential "Frequency Domain "method is also called" swept source "method referred to as.

In contrast, the "time domain" method can be used depending on the used Divide the detector into simultaneous and sequential methods, always using a broadband light source. While in the simultaneous "time domain" method, the expanded measuring beam falls on a diode, CCD or CMOS array, the measuring beam in the sequential "time domain" method via an interferometric beam splitter and a movable mirror in the reference arm to a simple, steered highly sensitive diode. This process is also referred to as "en-face" OCT.

Of the Great technological advantage of OCT is the decoupling the depth resolution of the transverse resolution. In contrast to microscopy, this allows the three-dimensional structure of the object to be examined. The purely reflexive and thus non-contact measurement allows the Generation of microscopic images of living tissue (in vivo).

In publications of AF Fercher and coworkers ("Measurement of optical distances by optical spectrum modulation", Proc. SPIE Vol. 2083, 263-267, 1993) the Fourier optical OCT method in general and also the special determination of the coherence function of the light reflected by the eye by inverse Fourier transformation of the spectral intensity distribution have been described ( "In Vivo Optical Coherence Tomography in Ophthalmology", Bellingham, WA: SPIE. pp. 355-370, ISBN 0-8194-1379-8, 1993 ).

The use of the Fourier transform method, specifically for measuring intraocular distances along a single beam through the pupil, has been used by AF Fercher et al ("Measurement of Intraocular Distances by Backscattering Spectral Interferometry", Opt. Commun. 117, 43-48, 1995 ) and by G. Häusler and MW Lindner for the production of OCT images ("Coherence RADAR" and "Spectral RADAR" new tools for dermatological diagnosis, J. Biomed., Opt. 3 (1), 21-31, 1998). ,

In the DE 43 09 056 A1 A method for determining the distance and scattering intensity of scattering points is described, in which the distance and the local scattering intensity are determined by Fourier transformation of the spectrum by wavelength.

A method in which three-dimensional images of the retina can be synthesized from En-face OCT images has been developed by AG Podoleanu, JA Rogers, DA Jackson, and S. Dunne ("Three dimensional OCT images from retina and skin", Opt. Express, 7, pp. 292-298, 2000). ,

A parallel OCT method, which also uses a step reference mirror is in the US 6,268,921 B1 described. The step reference mirror is used here for realizing the depth scan in the so-called Time Domain OCT. Accordingly, the step sizes are also significantly larger than λ / 8. In addition, the steps are not distributed with periodically recurring overall heights but are distributed step-like over the entire surface. The phase shifter still used in this solution has the same effect on the entire reference or measuring arm. Of course, these differences arise from the other problem presented there.

A similar method based on piezoelectric phase-shifting phase measurement is the content of US 6,377,349 B1 , In this solution, the reference mirror is moved piezoelectrically. However, this shift and the required additional exposures and multiple readout of the photodetector array take time, resulting in motion artifacts in living objects such as the eye.

A conventional OCT method for determining the dimensions of the anterior segment of the eye, using a slit lamp and a hand-held device, has been proposed by S. Radhakrishnan and others ("Real time optical coherence tomography of the anterior segment using hand-held and slit-lamp adapted systems", Proc. SPIE 4619, 227-229, 2002). described. The Time Domain OCT-based device works very fast and delivers eight frames per second. For example, for a three-dimensional representation of the anterior eye structure, the 8 images per second can be distributed equidistantly to the entire pupil; then you need about 1 second to record data. In contrast, the method underlying the present application can register the required data in milliseconds.

In the case of optical measuring instruments based on short-coherent methods, the interferometer principle is used according to the dual beam method. This method is non-contact and works with the highest accuracy. Solutions based on this measurement principle are described, for example, in US Pat DE 198 12 297 C2 . DE 103 60 570 A1 and WO 2004/071286 A1 ,

The in the two writings US 2008/0007691 A1 and US 2008/0007692 A1 described solutions relate to devices and methods for spectral measurement of the fundus Mes. The generation of different, spectral fundus images facilitates the identification of the parts and layers of the eye and in particular the fundus which have different spectral properties. The solution has, among other things an illumination source for generating a wavelength tunable light beam, an image acquisition unit for receiving a series of fundus images at different wavelengths, and an image processing and storage unit. To improve the fundus recordings, a series of spectral fundus images of the different wavelengths are taken while the lighting conditions change slightly. The change in the illumination conditions can also mean, for example, an increase or decrease in the wavelength in a specific wavelength range. Following this, the recorded fundus images are corrected accordingly so that they contain the same image detail. In addition, the fundus images are optimized using various image editing tools. The present solution thus ensures that particular parts in a fundus image, such as retinal arteries or veins in the retina, the optic nerve head, the choroid, or the macular region can be uniquely and precisely identified based on their spectral characteristics.

The in the US 2008/0204655 A1 described solution relates to a device for observation, image acquisition and image processing of the fundus of an eye. The apparatus described is capable of generating a tomographic image of a fundus of the eye to derive therefrom optical information on a condition of a point of the eye, to calculate the magnification of the optical system of the eye and to analyze the tomographic images. To generate the tomographic, 2-dimensional images of the fund, the solution has the usual units for lighting and for image acquisition, image processing and image storage on an OCT unit for the A-scan and a scan unit for the B-scan. In this case, the light source for observation emits illumination light having a wavelength in the visible wavelength range, for example between 400 and 700 nm and for imaging with a wavelength in the near infrared range, for example between 700 and 800 nm.

The in the two writings US 7,365,856 B2 and US 2006/0228011 A1 solutions described relate to optical coherence tomography (OCT). Thereby effects caused by movement of the sample are corrected. While a first series of A-scans is realized in such a short time that appreciable movement of the sample does not occur, a second series of A-scans of overlapping regions is so extensive that movements of the sample may occur. To compensate for any movement of the sample, first-row A-scans are randomly compared to A-scans from the second row based on a similarity analysis, and the A-scan comparison pair must include the same region of the sample. If no sample movement has taken place, it can be assumed that the course of the imaging scan pattern is identical, with the scanner in the same position, whereas movement of the sample results in that the imaging scan pattern for both A- Scans differ, especially against each other. From the randomly found "movement" of the imaging scan pattern and the resulting up-to-date information on the amount and direction of displacement of the sample, the actual movement of the sample can be interpolated. On the basis of the thus determined curve of the movement of the sample, a 3D image of the fundus, which is free of motion artifacts, can be determined.

The prior art discloses another noninvasive diagnostic imaging technique using a Confocal Scanning Laser Ophthalmoscope (cSLO). To A. Bindewald et al. ("CSLO fundus autofluorescence imaging methodological advances of confocal scanning laser ophthalmoscopy", Ophthalmologist 2005/102, pages 259-264) In addition to fluorescein or indocyanine green angiography, a confocal scanning laser ophthalmoscope can also be used to detect various retinal diseases from the fundus autofluorescence images (FAF images) produced. By excitation with light of a suitable wavelength and the appropriate filters, various retinal diseases can be detected by the cSLO system. Thus, for example, FAF images are recorded with a cSLO system, in which instead of the argon laser, a solid-state laser for generating the excitation laser light (488 nm) is used. The FAF images are detected via a cut-off filter above 500 nm. The new cSLO system achieves a resolution of up to 5 μm / pixel. Changes in topographic FAF intensity distribution are found in a variety of retinal pathologies, such as age-related macular degeneration (AMD), macular edema, and genetically determined retinopathy. Also in this method scattering profiles are evaluated from the response signal. Since this backscatter due to the refractive index jumps is particularly high at the optical interfaces, the determination of the optical path lengths between the interfaces is thus also possible.

As a result of both the OCT methods and the confocal methods, accurate values of axial distances in optical path lengths are obtained. While the deviations in the OCT method are below the coherence length, the deviations in the confocal methods, depending on the quality of the scattered light suppression, although something worse, but are also still in the lower micron range. Thus, a sufficiently good resolution of media on the eye, such. B. of blood vessels guaranteed.

The Refractive indices of the optical media such. B. the cornea, the Aqueous humor, the lens and the vitreous are well known and defined, for example, in the model of the Gullstrand eye.

at become the known prior art solutions through several, side by side, so-called depth scans sectional images the media of the eye generated up to 3D representations. in-depth or A-scans, to create cross-sectional images of the eye in the direction its optical axis, provide accurate readings, regardless whether the scan along the optical axis (depth or A direction) or at the pupil edge. The conversion of the determined optical Path lengths in path lengths in air take place via the refractive index of the respective optical media.

adversely affects in the known solutions, however, that optical defects on the eye, such as refractive error, astigmatism or even local defects cause the sectional images can show distortions in the lateral direction. These Distortions are local and individual to each human Eye.

Of the present invention is based on the object, a solution to develop, with the disadvantages of the known prior art be fixed, so that an absolute determination of sizes on the eye also in the lateral direction with high accuracy can and the biometric, two- or three-dimensional representations based on absolute, error-free measured values.

According to the invention the object by the features of the independent claims solved. Preferred developments and refinements are Subject of the dependent claims.

at the method according to the invention for the determination absolute measurements of an eye, based on absolute measurement data local depth or A-scans as well as known media structures of an eye, become known geometry features of the structures of Media of the eye with the data obtained from the local depth data. or A-scans of reconstructed geometric features compared, from the determined deviations of the geometry features local scaling factors determined and with the help of which the media of an eye so reconstructed that 2D or 3D representations of the media of an eye in all directions have absolute readings.

The described method is the absolute, highly accurate determination of sizes on the eye, both in axial as well in lateral direction. Resulting in possible biometric, Two- or three-dimensional representations are thus based on absolute, error-free measured values.

For The procedure is irrelevant, as for the determination required local depth or A-scans are generated. Consequently the described method can in principle also be used, if the local depths required for the determination or A-scans with an ultrasound device, a scanning laser ophthalmoscope, a fundus camera o. Ä. Are generated.

When Optical methods offer both the OCT method as well as the confocal measuring method, the exact values of axial Distances in the eye and thus exact optical path lengths deliver. While the deviations in OCT procedures below are the coherence length, these are confocal Method, depending on the quality of Stray light suppression, slightly larger than in the OCT method, but are also in the lower micron range and are therefore completely sufficient.

• – Vermessung des Nervenfaserkopfes zur Glaukomdiagnose,
• – näherungsweise Volumenmessungen von Ödemen und anderen Pathologien,
• – Nervenfaserschichtdickenmessungen und Darstellung,
• – Gefäßdiagnostik,
• – Blutflussgeschwindigkeitsmessungen oder auch
• – Kammerwinkel- und Vorderkammertiefenmessung zur Anpassung von Intraokularlinsen (IOL).

By applying the method according to the invention, a wide variety of measuring tasks can be implemented independently of the ophthalmic measuring device used, such as, for example:

• Measurement of the nerve fiber head for glaucoma diagnosis,
• - approximate volume measurements of edema and other pathologies,
• - Nerve fiber layer thickness measurements and representation,
• - vascular diagnostics,
• - Blood flow velocity measurements or also
• - Chamber angle and anterior chamber depth measurement for adjustment of intraocular lenses (IOL).

The Invention will be described below with reference to embodiments described in more detail.

at the method according to the invention for the determination absolute measurements of an eye, based on absolute measurement data local depth or A-scans as well as known media structures of an eye, become known geometry features of the structures of Media of the eye, with those from the measured data of the local depth or A-scans of reconstructed geometric features compared, from the determined deviations of the geometry features local scaling factors determined and reconstructed the media of an eye with their help so that 2D or 3D representations of the media of an eye in all directions have absolute readings.

The known geometric features of the structures of the media of an eye become from the measurement data of the local depth or A-scans within reconstructed a small volume.

At the Human eye tissue properties are present locally be characterized and have typical structures. These typical structures are at a visually faulty figure visibly changed. Erroneous distortion can thus quantified and with a local scaling factor be compensated. With "local" or "within a small volume "is defined as a volume which is at least one geometry feature of a structure of a medium of an eye completely.

When Structures of the media of an eye are preferably blood vessels, Chopsticks or suppositories or nerve cells used.

there have the vessels as a typical structure in shape of arteries and veins at the retina in general a round Cross section or oblique sectional images an elliptical Cross-section on. By extraction of the vascular tree can be the angle of orientation of the vessels determine the optical axis of the eye. vessels which run parallel to the optical axis of the eye, thus have in sectional images on a circular shape.

at occurring, local distortions indicate the vessels in the images of the depth or A-scans one of the circular Shape deviating shape. In this case, a distortion factor varies until the vessel section is circular.

at Vessels that run obliquely to the optical axis, The typical structures have elliptical cross sections, with one defined axis ratio.

occurring, local distortions lead to deviations from this defined one Axis ratio, which also uses local distortion factors have it corrected.

Preferably are used for averaging the local scale factor determined several vessels from a local environment. This is especially useful if the typical structures have statistical deviations from the typical structure.

With Help of the determined scaling factors can be found in the Representations of the diagnostic results optical aberrations of the To be corrected. In a practicable implementation of the correction In a 2D representation, each subarea is individualized with a factor scales; Preferably, a subdivision takes place in the X and Y directions. One obtains a matrix of scaling factors, each element the matrix assigned an image area of the recording to be scaled is. For 3D shots, this matrix gets one another dimension. Likewise, assignments in polar coordinates are conceivable.

In In a particular embodiment, the determination of the local Scaling factors from the deviations of the geometry features by optimization calculation. The scaling factors are varied until the reconstructed geometric features with the known, predetermined Geometry features match. The for the Optimization calculations required geometry features can Here, for example, come from OCT or confocal recordings.

The local scaling factors are at least for one localized area determines the size the structures of the media selected for comparison Correspond to the eye.

In a further advantageous embodiment are preferably 25, at least 9 local, evenly distributed Scaling factors determined by comparison and optimization calculation. The determination of additional intervening scaling factors takes place with the aid of known interpolation methods.

Even though the accuracy of the reconstructed 2D or 3D representations of the Media of an eye through the largest possible Number of calculated by comparison and optimization calculation Scaling factors can be increased, it has been shown that the number of 25 is quite sufficient. additional Scaling factors can be significant through interpolation be determined faster.

It It goes without saying that scaling factors depend on the media of the eye to be imaged are each to be newly determined, because the different media do not necessarily have the same structural features exhibit. For determining local scaling factors for different media of the eye are appropriate to select different structures for their determination.

Under It may also happen that the media of the eye has no suitable structure at the point concerned. In In this case, the scaling factor may be at an adjacent location be determined and interpolated. In narrow limits, it is even possible that the scaling factor thus determined extrapolates becomes.

Already determined scaling factors for Correction of distortion can be transferred to other areas of the eye with simple, optical models of the eye. For example, with the imaging equation, the local scaling factor, which was determined on the basis of the arteries and / or veins in the retina, can be transferred to the nerve tissue lying in front of it.

Out the detected local distortions and the well-known optical structure of the eye can be typical optical errors of the eye, such as ametropia and astigmatism determine and assign to the respective patient's eye.

There the determined, individual optical errors of patient eyes thus also accessible to other ophthalmic devices These can also be done for to use the absolute correction of fundus images.

In a particularly advantageous embodiment, the media of the Auges external and / or molecular markers added as known Serve geometry feature.

While External markers are separate substances that enter the human material cycle are introduced, molecular markers go after introduction chemical bonds with existing body substances.

there the markers to be inserted are to be selected so that these recorded and resolved with the measuring method used can be. For measurement with an OCT method would be markers of the order of 5 microns up to the 1/10 mm range makes sense. In addition, the Marker a suitable scattering or absorption behavior or fluorescence behavior in the exploitation of fluorescence also the possibility of so-called fluorescence resonance energy transfer (short FREI) application can find.

Preferably the external markers have a spherical shape of defined size on. This has the advantage that the external marker in all images, regardless of the orientation of the structure as a circular Object is recognizable. Due to the defined size the recognition of aberrations is further improved. Considering of refractive index and dispersion is, for example, the use of Latex beads conceivable.

Under External markers or even molecular markers are in molecular biology Understand substances that are clearly identifiable and their Place in the genome are known. The markers are so genetically engineered built in, attached or added to their presence in one Organism can be easily recognized. The recognizability can thereby by linking such markers to genes generated by fluorescence can be improved.

Preferably the external markers in the desired media of the Eye only available for a minimum measuring time and Build without complications and side effects in the body and are biocompatible.

In In another advantageous embodiment, the local depth or A-scans used to detect eye movements and or compensate. For this purpose, in the individual pictures of the local depth or A-scans one and the same geometry feature of a structure selected. For the detection of eye movements, it is checked whether the Geometry feature in the single images located in the same place, because this is only the case if no eye movement occurred Has.

To the Compensation of eye movements become the frames of the local Depth and A scans are superimposed on each other cover the geometry features. This can improve the accuracy of the determination from absolute sizes on the eye also in lateral Direction to be improved.

additionally to this embodiment, the method can be used To detect vessel courses by the Single images of the local depth or A-scans of one and the same Vessel are placed one above the other and indeed, without these being shifted against each other. From the determined Vascular history can be the smallest Detect cross section.

Of Furthermore, it is possible for those from the local Depth or A-scans determined vessel course an average ratio between lateral and axial To determine expansion of the vessel. For this Size ratio can be derived whether a calibration is required with high probability.

So For example, after a ring around The papilla was scanned the near-surface vessels around the papilla examined for this ratio be, where ratios between lateral and axial Expansion of less than 1 suggests that a calibration is still required.

In a particularly advantageous embodiment, the determined local scaling factors and / or determined therefrom 2D or 3D representations of the media of an eye with absolute readings in all directions, to other ophthalmic systems become.

Become For example, the absolute measurement data of local depth or A-scans used on the basis of an OCT method, local scaling factors and / or 2D or 3D representations of the media of an eye with absolute To determine measured values in all directions, they can also be used to create a fundus camera for measurements or images to scale so as an absolute Funduskamerakalibrierung in lateral direction to reach this eye.

With the method according to the invention becomes a solution provided with the disadvantages of the known Prior art be remedied so that an absolute determination of sizes on the eye also in the lateral direction with high accuracy can be done and the biometric, two- or also three-dimensional representations on absolute, error-free Measurements are based.

there are absolute depth scans of optical biometry as well as well-known Features of structures on the eye used to measure the absolute also to ensure the lateral direction. Therefor local scaling factors are determined which are the individual, Describe optical errors of the human eye.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4235079 C2 [0004]
• - US 5321501 [0007]
• DE 4309056 A1 [0015]
• - US 6268921 B1 [0017]
• - US 6377349 B1 [0018]
• - DE 19812297 C2 [0020]
• DE 10360570 A1 [0020]
• WO 2004/071286 A1 [0020]
• US 2008/0007691 A1 [0021]
• US 2008/0007692 A1 [0021]
• US 2008/0204655 A1 [0022]
• - US 7365856 B2 [0023]
• US 2006/0228011 A1 [0023]

Cited non-patent literature

• AF Fercher and coworkers ("Measurement of optical distances by optical spectrum modulation", Proc. SPIE Vol. 2083, 263-267, 1993) [0013]
• - "In Vivo Optical Coherence Tomography in Ophthalmology", Bellingham, WA: SPIE. pp. 355-370, ISBN 0-8194-1379-8, 1993 [0013]
• AF Fercher and coworkers ("Measurement of Intraocular Distances by Backscattering Spectral Interferometry", Opt. Commun. 117, 43-48, 1995 [0014]
• G. Häusler and MW Lindner used for the production of OCT images ("Coherence RADAR" and "spectral RADAR" new tools for dermatological diagnosis, J. Biomed., Opt. 3 (1), 21-31, 1998) [0014 ]
• - Podoleanu AG, JA Rogers, DA Jackson, and S. Dunne ("Three dimensional OCT images from retina and skin", Opt. Express, 7, pp. 292-298, 2000). [0016]
• S. Radhakrishnan and others ("Real time optical coherence tomography of the anterior segment using hand-held and slit-lamp adapted systems", Proc. SPIE 4619, 227-229, 2002) [0019]
• - A. Bindewald et al. ("CSLO Fundus Autofluorescence Imaging Methodological Developments of Confocal Scanning Laser Ophthalmoscopy", Ophthalmologist 2005/102, pages 259-264) [0024]

Claims (15)

Method for determining absolute measured values of an eye, based on absolute measurement data of local depth or A-scans and known structures of the media of an eye, characterized in that the structures of the media of the eye have known geometric features that match those of the measured data of the local Depth or A-scans are reconstructed geometry features are determined from the determined deviations of the geometry features local scaling factors and that with their help, the media of an eye are reconstructed so that 2D or 3D representations of the media of an eye in all directions absolute Have measured values. Method according to claim 1, characterized in that that the known geometric features of the structures of the media Eye from the measurement data of the local depth or A-scans within a small volume can be reconstructed. Method according to claim 1 or 2, characterized that as structures of the media of an eye blood vessels, Chopsticks or suppositories or nerve cells be used. Method according to at least one of the aforementioned Claims, characterized in that the determination the local scaling factors from the deviations of the geometry features by optimization calculation done by the scaling factors until the reconstructed geometry features are varied agree with the known, predetermined geometric features. Method according to at least one of the aforementioned Claims, characterized in that a local scaling factor determined at least for a lo limited area will be the size of the selected for comparison Structure of the media of the eye corresponds. Method according to at least one of the aforementioned Claims, characterized in that preferably 25, at least 9 local, evenly distributed Scaling factors through comparison and optimization calculation and additional scaling factors determined by interpolation become. Method according to at least one of the aforementioned Claims, characterized in that the local scaling factors are to be determined for different media of the eye correspondingly different structures for their Determination to be selected. Method according to at least one of the aforementioned Claims, characterized in that the scaling factors for media of the eye that do not have suitable structures, determined and interpolated at neighboring locations, within narrow limits extrapolated or transferred with simple optical models become. Method according to at least one of the aforementioned Claims, characterized in that the media of External and / or molecular markers may be added to the eye serve known geometry feature. Method according to at least one of the aforementioned Claims, characterized in that the external markers preferably a spherical shape of defined size exhibit. Method according to at least one of the aforementioned Claims, characterized in that the local depth or A-scans are used to detect eye movements, by entering in the images of the local depth or A-scans and the same geometry feature of a structure selected and is controlled, whether this in the frames at the same place. Method according to at least one of the aforementioned Claims, characterized in that the local depth or A-scans are used to compensate for eye movements, by entering in the images of the local depth or A-scans and the same geometry feature of a structure selected and the frames are superimposed so that the geometry features coincide. Method according to at least one of the aforementioned Claims, characterized in that the local depth or A scans are used to vessel trajectories detected by the individual images of the local depth or A-scans of one and the same vessel on top of each other be placed. Method according to at least one of the aforementioned Claims, characterized in that the local depth or A scans are used from the vessel course to detect the smallest cross-section. Method according to at least one of the aforementioned Claims, characterized in that the determined local scaling factors and / or the resulting 2D or 3D representations of the media of an eye with absolute measurements in all directions, transferable to other ophthalmic systems are.